Simultaneous quantitative determination of NG,NG-dimethyl-l-arginine or asymmetric dimethylarginine and related pathway's metabolites in biological fluids by ultrahigh-performance liquid chromatography/electrospray ionization-tandem mass spectrometry

Abstract: Background: Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide (NO) formation inhibitor, has emerged as a promising biomarker of NO-associated endothelial dysfunction in cardiovascular diseases as well in chronic renal failure. The interest in potentially fundamental role of this metabolite, in basic and clinical research, led to the development of numerous analytical methods for the quantitative determination of ADMA and dimethylarginines in biological systems, notably plasma, serum and urine. Objectives: The aim of this work was to present a simple, fast and accurate UPLC–tandem-MS-based method for the simultaneous determination and quantification of arginine, ADMA, SDMA, NMMA, homo-arginine and citrulline. This method is designed for high sample throughput of only 10μL of human plasma, serum or urine. Methods: The analysis time is reduced to 1.9min by an ultrahigh-performance liquid chromatography run coupled with electrospray ionization (ESI) in the positive mode tandem mass spectrometry detection. Results: The method was validated in plasma, serum and urine. Correlation coefficients (r 2) of the calibration curves in all matrices considered ranged from 0.9810 to 0.9993. Inter- and intra-assay precision, accuracy, recovery and carry-over were evaluated for validation. The LOD was 0.01μM for all compounds in water, plasma and serum and 0.1μM in urine. The LOQ was 0.05μM for ADMA, SDMA, NMMA and H-Arg and 0.5μM for Arg and Cit in water, plasma and serum; while in urine was 0.1μM for ADMA, SDMA, NMMA and H-Arg and 0.5μM for Arg and Cit. The precision was ranged from 1% to 15% expressed as CV% and the accuracy (bias %) was <±7% for all added concentrations with the exception of NMMA (−10%). ADMA mean plasma levels, measured in healthy adults and newborns, were in accord with literature data published: (M±SD) 0.56±0.10μM and 0.84±0.21μM, respectively, showing that ADMA levels in plasma decreased with age. In serum we have similar data (0.54±0.18μM and 1.14±0.36μM), while in neonatal urine ADMA was 11.98±7.13μmolmmol−1 creatinine. Conclusions: Data from calibration curves and method validation reveal that the method is accurate and precise. The fast run time, the feasibility of high sample throughput and the small amount of sample required make this method very suitable for routine analysis in the clinical setting. [Copyright &y& Elsevier]